【摘要】 为研究不同压裂介质影响下的绝对应力测值,利用大尺寸真三轴模拟水压致裂试验系统,用清水及密度分别为1.1、1.2、1.3、1.4 g/cm3的泥浆介质对400 mm×400 mm×400 mm的花岗岩试样进行了水压致裂室内试验,成功获取了连续的压力-时间曲线。利用6种方法识别压力-时间曲线的闭合压力点,与实加最小水平主应力(h S 5 MPa)对比,得出单切线等4种方法较为符合实际情况;在考虑试验系统柔度影响前提下,对比了实测和理论重张压力;最后分析了在持续泵压作用下岩石裂缝延伸的压力。试验结果表明,密度为1.1、1.2 g/cm3的泥浆介质对压力特征参数的取值影响较小,误差不超过1 MPa,但密度为1.3、1.4 g/cm3的泥浆介质对特征参数值影响很大。试验结果对水压致裂地应力测量技术在不同压裂介质影响下的适用性有重要的指导意义。更多还原

【Abstract】 To study absolute rock stress measurement under different fracture media,by using large chamber true triaxial hydraulic-pressure fracture simulating system,a hydraulic fracturing experiment in lab is carried out with 400 mm×400 mm×400 mm granite specimen on effect of the water and the relative densities of 1.1 g/cm3,1.2 g/cm3,1.3 g/cm3,1.4 g/cm3respectively,the continuous pressure-time curves are obtained.By using 6 kinds of methods,closure pressure points on pressure-time curve are distinguished;4 kinds of methods,for example single tangent,are consistent with actual situation through contrasting the actual minimum horizontal principal stress(h S 5 MPa).Considering the effect of experimental flexibility,the measured reopening pressure and theoretical reopening pressure are contrasted.Finally,the pressure of extended rock fissures in continuous pumping pressure is analyzed.The experimental results show that the slurry relative densities of 1.1 g/cm3,1.2 g/cm3have little effect on pressure characteristic parameters;and its error is no more than 1 MPa;the slurries with relative densities of of 1.3 g/cm3,1.4 g/cm3have great effect on values of pressure characteristic parameters.The experimental results have an important guiding meaning for application of hydraulic fracturing technology to measurement of absolute stress under different fracture media.更多还原